Propeller for helicopters



-May 18,1926. I' N l G. s. SARGENT.

PROPELLER FOR HELICOPTERS 2 Sheets-Sheet 1 Filed NOV. 18 1925 May 18 1926.

` G. S. SARGENT PROPELLER FOR HELIooPTERs Filed Nov. 18, 1925 2 Smetssheet 2 the' propeller;

Patented May I 18', 1926.

UNITED STATE s PATENT oFFlcE.- l

GEORGE S. SABGENT, CHICGO, ILLINOIS.

PROPELLER FOR 'HELICOPTER i Application led November 18, 1925. Serial No. 69,748.

to provide an improv/ed propeller which presents extensive surfaces for engagement with the air, and which. because of the arrangment, formation and movements of such surfaces, is capable ofurl Voperating through the air with practically no relative slippage. While the pro eller of the invention is primarily intende for use With helicopters, it is. also susceptible ofv use With other types of flyingmachines.

4Another object is to provide an improved propeller which is light, strong and durable in construction, is compact in arrangement, and is highly efficient in operation. v

Other objects'and advantages not herein specifically referred to will be evident to those skilled in the art upon an understanding of the nature of the propeller; the' invention residing substantially in the novel formation` combination and arrangement of parts hereinafter described.

One form of the invention is presented for the, purpose ofexemplilication, but it Will be understood that the invention is not limited in 'its numerous practical applications to the Nprecise detail/s of construction shown in connection Withfthat form, a -such details obviously may be modified in virions ways without eparting from the comprehensive scope` of the invention as defined,

in the appended claims.

lnthe accompanying drawings- Fig. 1 is a diametrical section taken through a propeller constructed in' accordance with the invention; y, Fig. 2 is a rear view of the propeller; Fig. 3- is a side view ofthe outer section of Fig. .4 is a similar view of the middle section. of the propeller;

Fig.4 5 is a similar view of the inner sec- Y .tion of the propeller; and

Fig. 6 is a typical section through any one 7 ofthe propeller blades! j.

The propeller ofthe invention isoffsectional construction, .and includes an oZuter section 10,'a middle section 11, and an inner ,section 12. The sections are of generally annular form, and arenestedv concentrically in' lap ed relation to eachother, preferably with i 'a thrust-bearing A medial portion of the shaft 17 A bevele outer-section. a.' little' 1n advance of the middle section, and t-he middle section 1n -t-urn a littlein advance of the inner section, all as shown in Figs. l and 2.. C'

.their entering edges 15 to their trailing edges 16. The trailing edges of the blades preferably are set away from the axis of the propeller a greater distance than the entering edges, which arrangement renders the blades slightly spiral as well vas helical' relative to such axis. The iframe work of each section is suitably stream-lined and may advantageously consist of a plurality of connected ring members, the frame Work of the middle section being of substantially' cylindrical form, and the frameworks of. the inner and vbuter sections being of slightly conical form with. the frame workofthe outer section'tapering toward the front ot the propeller and that of the innersection tapering toward the rear of the same.

The sections are adapted to be rotated at high speed with the outer and inner sec'- tions moving in one direction andthe middle section moving in the opposite direction, the speed of rotation for eachsection preferably being such relative to the otherctions as to give approximately the samev linear spped to t-he entering edges of the blades of a of the sections. The mechanisnf for rotating the sections will of course vary in character,depending upon the type of flying machine with which the propeller is to be used. If the propeller is tobe used for instance with a helicopter,

a mechanismsuch as shown in ig. 1 may advantageously be emplo ed. Tie mechaism therein shown inclu es a main operating shaft 17 ,which 1s positioned transversely infront of the propeller and carries three bevel gears which mesh with three similar gears connected with the sections.

Thel frame work `of the innersection is supported from a hub 18 by means of aplurality of intervening 'spokes 19, and-- the hub 18 1s secured to the rearend of a shaft 20 which seats at'the v front end thereof in member 21 journaled on a gear 2 2 Seanad teV the' front end off-the Vshaft 20, and meshes with a relatively large bevel gear 23 which lis secured to the shaft 17 at one side of the axis of the propeller. A sleeve 24 is journaled on the shaft 2O between the hub 18 and the gear 22, and the frame work of the middle section is supported from a hub 25 which is secured to the rear 'end of the sleeve 211. A bevel gear 26 is secured to the front end of the sleeve 24, and meshes with a bevel gear 27 of about the same size which is secured to the sleeve 17 on the other side of the axis.

The frame work of the outer section is A supported from an/ outwardly grooved ring ber and are carried by two supporting brackets 32 journaled on the shaft 17 at opposite sides of the axis of the propeller. A bevel gear 33 is provided on the front face of the ring member 28, and such gear meshes with a relatively small bevel gear 34 which is secured to the shaft 17 at the same side ot' the axis of the propeller as the gear 23.

The supporting Vbrackets 32 are held against angular movement about the axis of the shaft 17,1but may be adjusted angularly in unison thereabout by any suitable means acting through twosleeves 35 to which the brackets are secured, in order to vary the position of the axis of the propeller, whereby the propeller may be set in a substantially vertical pesition'formoving the associated helicopter vertically and then changed to a substantially horizontal position for moving the helicopter horizontally when elevated.

It will be evident from the construction above described that, when the shaft 17 is rotated, the gears 23, 27 and 34 thereon will rotate the gears 22, 26 and 33, and the sections of the propeller will be correspondingly rotated, the outer and inner sections being moved in one direction and the middle section being moved in the opposite direction.

In operation, the propeller of the invention is capable of delivering a strong and steady thrust, as it engages efficiently with all parts of the air column with which it comes into contact. In the operation of the ordinary propeller, however, a considerable amount of slippage and lateral dissipation in theair 'columnis .experienced because only -the-"tipsof the' blades of f'sil'h a' prof peller engag to any extent with the air, and a substantial part of the air so engaged is deflected laterally toward or away from the propeller axis instead of being forced rearwardly. The shape and arrangement of the blades in the present propeller is such as to effect an extended screwing engagement with the air which to a large extent eliminates slippage and lateral dissipation of the air, owing to the formation and relative disposition of the nested sections and the transverse curvature and rearward diversions of the oppositely moving blades.

I claim:

1. A propeller, comprising three concentrically arranged outer middle and inner sections, each of which is set in advance of the inwardly adjoining section and yis provided with a plurality of helically disposed blades which are concave in cross section and are widened progressively from their entering to their trailing edges, and means for rotating the outer and inner sections in one. direction and the middle section in the opposite direction with the entering edges of the blades of all of the sections moving vat substantially the same speed.

2. A propeller, comprising a plurality of concentrically arranged sections, each of which is provided with a plurality of helically disposed blades, an operating shaft positioned transversely of the axis of the propeller adjacent one end of the same, bevel gears corresponding in number to the sections secured to the shaft,'other bevel gears connected for rotation with the sections and meshed with the gears on the shaft, and means for varying the angular position of the axis of the propeller about the axis of the shaft.

3. A propeller, comprising three concentrically arranged sections, each of which is provided with a plurality of helically disposed blades, an operating shaft positioned transversely of the axis of the propeller in lrontof the same, three bevel gears secured to the shaft with two of the gears at one side of the axis of the propeller and the other gear at the opposite side of the axis, and three other bevel gears connected for rotation with the sections and meshed with 'the gears on the shaft, the second mentioned GEORGE si sanenivr, 

